Infrastructure as a service (IAAS) is a service that allows a service provider to sell computing services and resources. IAAS services are generally provided without requiring the end user to know the location and other details of the provided infrastructure and allow for the utilized resources to be stored and deployed on server systems or databases that are remotely provisioned.
An IAAS is generally implemented to take advantages of economies of scale and may be used to (1) minimize the total cost of ownership of the provided infrastructure by optimizing the allocation of resources to virtualized systems (e.g., VMs) that are utilized to provide the services, and (2) meet the defined SLAs for a VM to the extent possible. Typically, if an SLA associated with a requested VM is infringed, then a certain fine is imposed against the service provider for breach of the SLA-defined provisions.
Given the limitations associated with the underlying infrastructure, it is desirable to allocate as much workload as possible to the virtualized resources, while keeping the SLA infringements under the limit permitted by the respective SLAs. The over commitment of resources has to be properly done in order to be most effective in terms of the minimization of the total cost of ownership, while generating controlled and acceptable levels of SLA infringement.